De Havilland Canada CP-121 Trackers

The Grumman S-2 Tracker (previously S2F) was the first purpose-built, single airframe anti-submarine warfare (ASW) aircraft to enter service with the US Navy.

Its predecessor, the AF-2 Guardian was the first purpose-built aircraft system for ASW, using two airframes, one with the detection gear, and the other with the weapons.

CS2F-1
Initial production run of anti-submarine warfare aircraft for Canada based on S2F-1. 42 built by De Havilland Canada.

CP-121
New designation given to all CS2F-1, -2, and -3 aircraft following unification of Canadian military in 1968.